A special U.N. human rights investigator will visit the United States this month to probe racism, an issue that has forced its way into the race to secure the Democratic Party's presidential nomination.

The United Nations said Doudou Diene would meet federal and local officials, as well as lawmakers and judicial authorities during the May 19-June 6 visit.

"The special rapporteur will...gather first-hand information on issues related to racism, racial discrimination, xenophobia and related intolerance," a U.N. statement said on Friday.

His three-week visit, at U.S. government invitation, will cover eight cities -- Washington D.C., New York, Chicago, Omaha, Los Angeles, New Orleans, Miami and San Juan, Puerto Rico.

Race has become a central issue in the U.S. election cycle because Sen. Barack Obama, the frontrunner in the battle for the Democratic nomination battle, stands to become the country's first African American president.

His campaign has increased turnout among black voters but has also turned off some white voters in a country with a history of slavery and racial segregation.

Diene, a Senegalese lawyer who has served in the independent post since 2002, will report his findings to the U.N. Human Rights Council next year.

However, the United Nations has almost no clout when it comes to U.S. domestic affairs and is widely perceived by many as interfering. The United States is not among the 47 member states of the Geneva-based forum, but has observer status.

In a report last year he said Islamophobia had grown worldwide since the September 11 2001 attacks on the United States, carried out by al-Qaeda militants.

DEATH PENALTY

A U.N. panel which examined the U.S. record on racial discrimination last March urged the United States to halt racial profiling of Americans of Arab, Muslim and South Asian descent and to ensure immigrants and non-nationals are not mistreated.

It also said America should impose a moratorium on the death penalty and stop sentencing young offenders to life in prison until it can root out racial bias from its justice system.

Racial minorities were more likely than whites to be sentenced to death or to life without parole as juveniles, according to the U.N. Committee on the Elimination of Racial Discrimination. It monitors compliance with an international treaty which Washington ratified in 1994.

U.S. officials told the body, made up of 18 independent experts, that they were combating hate crimes such as displays of hangman's nooses and police brutality against minorities.

Some 800 racially motivated incidents against people perceived to be Arab, Muslim, Sikh or South Asian had been investigated since the September 11 attacks, they said at the time.

Substantial progress had been made over the years in addressing disparities in housing, education, employment and health care, according to a U.S. report submitted to the talks.